The objective of this proposal is to demonstrate the feasibility of a novel method for detection of human immunodeficiency virus (HIV) antibody in the body fluids. The method is based on the use of ultrasound to significantly increase the sensitivity and reduce time of analysis of conventional particle agglutination immunoassay. Ultrasound waves are used for both accelerating and monitoring of the agglutination process. Proposed technology exploits the sequence of physical phenomena in the ultrasonic standing wave field including (a) accumulation of particle aggregates in the nodes of the standing acoustic wave and acceleration of the agglutination process; (b) generation of microbubbles in the nodes of the standing acoustic wave, where the latex particle aggregates serve as microbubble nucleation centers; (c) the growth of the microbubbles in the ultrasonic field due to rectified diffusion of the dissolved gas from the liquid into the microbubble; and (d) the following cavitation activity which provides gigantic amplification of the "signal" indicating the formation of the particle aggregate due to antigen-antibody reaction. The immunoassay we propose to develop will be implemented in a simple, portable and inexpensive device based on the novel patented cylindrical resonator technology. Significantly, the method can be easily adapted to detect any target molecule for which antibodies can be raised. Preliminary studies confirmed feasibility of the major innovative components of the proposed technology and it is shown that the new method has significant commercial and scientific potential.